A nationwide rise in drink-spiking incidents has prompted the police to launch an advertising campaign to raise public awareness about the problem.
Hamilton city area controller Paul Carpenter said drink-spiking was becoming a common problem in bars and pubs throughout the country.
Nationwide statistics are not recorded, butHamilton police have spent the past year focusing on the issue.
Mr Carpenter said police received 22 complaints in that time, four involving allegations of sexual violation.
Investigations were continuing into the complaints, but it could be difficult to catch the offenders, especially if the cases were not reported immediately.
The nationwide advertising campaign, which runs on television and in cinemas for the next month, aims to get people thinking about just how easily, and quickly, spiking can occur.
"The main thing for us is crime prevention," said Mr Carpenter.
"We are trying to encourage people to keep themselves safe.
"That includes things like buying your own drink, never taking a drink from a stranger, watching your drink at all times and never leaving it unattended."
Mr Carpenter said the victims were not always young women. Men and older women had also been targeted.
Police urge anyone who thinks their drink has been spiked to report the matter immediately so tests can be done.
Most drugs cannot be traced in the body after about 12 hours.
Without evidence of drugs, a court conviction is highly unlikely, they say.
The advertising campaign follows last year's nationwide distribution of awareness posters in bars and pubs.
Drink-spiking:
* Drinks can be spiked in seconds with just a few drops of liquid or a sprinkling of powder.
* The drugs may not have any colour, smell or taste.
* You probably won't notice that your drink has been spiked, especially if you are intoxicated.
* The drugs can start to affect you within 10 to 20 minutes. You might feel dizzy, sleepy or relaxed. You might have a lack of inhibition or be open to suggestion.
* As the effects peak you might pass out and have memory loss the next day.
